Phenyliodonium Bis Research Articles

PIFA/Ar2Te2‐Mediated Synthesis of 3‐Aryltelluroindoles via Intramolecular Cyclization of 2‐Alkynylanilines

AbstractThe reaction of 2‐alkynylanilines with phenyliodonium bis(trifluoroacetate) (PIFA) and diaryl ditellurides was found to conveniently afford the corresponding 3‐aryltelluroindoles via oxidative cyclization/tellurolation. A plausible mechanism involving the in situ formation of the reactive ArTeOCOCF3 from the reaction of PIFA and diaryl ditellurides, and the subsequent oxidative C−N/C−Te bond formations was postulated.

Oxidative Deprotection of Benzyl Protecting Groups for Alcohols by an Electronically Tuned Nitroxyl-Radical Catalyst.

The oxidative deprotection of benzyl (Bn) groups using nitroxyl-radical catalyst 1 and co-oxidant phenyl iodonium bis(trifluoroacetate) (PIFA) is reported. This catalyst is highly active for the oxidation of benzylic ethers because of the electronic tuning on account of the electron-withdrawing ester groups next to the catalytically active center. This catalytic system promotes deprotections at ambient temperature and has a broad substrate scope, including substrates possessing hydrogenation-sensitive functional groups, while the deprotection hardly proceeds when using well-known nitroxyl-radical catalysts such as 2,2,6,6-tetramethylpiperidine N-oxyl (TEMPO). The 1/PIFA system also promotes the deprotection of several benzylic protecting groups, including 2-naphthylmethyl (NAP) and 4-methylbenzyl (MBn) groups. Catalyst 1 was also effective for the direct synthesis of ketones and aldehydes from Bn ethers via deprotected alcohols using an excess of the co-oxidant PIFA.

Diverse Site-Selective Transformation of Benzylic and Allylic Silyl Ethers via Organocatalytic Oxidation

We herein report nitroxyl-radical catalyst 1a, which recognizes the electronic properties of silyl ethers, thus enabling selective oxidation of benzylic and allylic silyl ethers, despite steric factors. A subsequent one-pot reduction accomplishes the formal deprotection to the corresponding benzylic and allylic alcohols. This catalytic system allows the direct oxidative desymmetrization of bis-benzylic and bis-allylic silyl ethers to access synthetically useful monoprotected conjugated aldehydes, which can be applied to one-pot enantioselective transformations. Mechanistic studies revealed that the highly electron-accepting oxoammonium species from 1a as well as the trifluoroacetate form of phenyl iodonium bis(trifluoroacetate) (PIFA) play key roles for the selectivity-determining hydride transfer step.

Oxidative Deprotection of p-Methoxybenzyl Ethers by a Nitroxyl Radical Catalyst

The oxidation of p-methoxybenzyl (PMB) ethers was achieved using a nitroxyl radical catalyst 1, which contains electron-withdrawing ester groups adjacent to the nitroxyl group. The oxidative deprotection of the PMB moieties on the hydroxy groups was observed upon treatment of 1 with one equivalent of the co-oxidant phenyl iodonium bis(trifluoroacetate) (PIFA). This system showed an excellent chemoselectivity profile for the deprotection of PMB ethers from a broad range of functional groups including diverse oxidation-sensitive moieties. The corresponding carbonyl compounds were obtained by treating the PMB-protected alcohols with 1 and an excess amount of PIFA.

Chemoselective Oxidation ofp-Methoxybenzyl Ethers by an Electronically Tuned Nitroxyl Radical Catalyst

The oxidation of p-methoxy benzyl (PMB) ethers was achieved using nitroxyl radical catalyst 1, which contains electron-withdrawing ester groups adjacent to the nitroxyl group. The oxidative deprotection of the PMB moieties on the hydroxy groups was observed upon treatment of 1 with 1 equiv of the co-oxidant phenyl iodonium bis(trifluoroacetate) (PIFA). The corresponding carbonyl compounds were obtained by treating the PMB-protected alcohols with 1 and an excess of PIFA.

Phenyl iodonium bis(perfluoroalkanesulphonyl)-methide-dimethyl sulphoxide complex-Its formation and X-ray structure analysis

Irradiation of phenyl iodonium bis(perfluoroalkanesulphonyl)methide in DMSO yields an 1:1 adduct, DMSO·PhIC(SO2RF)2 (2) which was confirmed by X-ray crystal structure analysis.

ChemInform Abstract: 1,1-Bis(phenylsulfonyl)-4-diethylamino-1,3-butadiene, a Fully Delocalized “Push-Pull” Diene.

Abstract The title compound is obtained from the reaction of phenyliodonium bis(phenylsulfonyl)methanide and diethylamine. Its structure and properties suggest that it is a fully delocalized system.

Rhodium(II)-Catalyzed Transylidation of Aryliodonium Ylides: Electronic Effects of Aryl Groups Determine Their Thermodynamic Stabilities

Intermolecular transylidations between aryliodonium ylides under catalytic conditions were developed. Heating a solution of phenyliodonium bis(trifluoromethylsulfonyl)methylide in a large amount (80 equiv) of a substituted iodobenzene in the presence of 5 mol % of rhodium(II) acetate as a catalyst transfers the bis(trifluoromethylsulfonyl)-methylidene group to the iodine(I) atom and affords a substituted aryliodonium ylide in a good yield. Reversible nature of the catalytic intermolecular transylidation makes it possible to evaluate the thermodynamic stability of aryliodonium ylides.

3+2] Cycloaddition of Phenyliodonium Bis(arylsulfonyl)methylides with α,β-Enones

The [3+2] cycloaddition of phenyliodonium bis(arylsulfonyl)methylides to α,β-enones affords exclusively TRANS, TRANS-configured 1-(arylsulfonyl)-2-aroyl-3-arylindanes. The initial electrophilic attack of the iodonium ylide on the alkenyl double bond of the chalcone, followed by cyclization of the dipolar species, and subsequent ejection of iodobenzene and sulfur dioxide, stereoselectively affords the indane cycloadduct.

Oxidative-substitution reactions of electron-rich aromatic compounds with BF 3-activated iodonium ylides

The treatment of electron-rich aromatic substrates with phenyliodonium bis(carbonyl)methylides in the presence of Et 2O·BF 3 leads to bis(carbonyl)alkylation of the aromatic nucleus.

Synthesis of (S)-(−)-N-acetylcolchinol using intramolecular biaryl oxidative coupling

An asymmetric synthesis of the tubulin polymerisation inhibitor (S)-(-)-N-acetylcolchinol is reported based on an intramolecular biaryl oxidative coupling of a 1,3-diarylpropyl acetamide intermediate using phenyliodonium bis(trifluoroacetate) as the final step. Three syntheses of the penultimate 1,3-diarylpropyl acetamide intermediate (S)-(-)-N-[1-[3-(tert-butyldimethylsilyloxy)phenyl)]-3-(3,4,5-trimethoxyphenyl)propyl] acetamide are described which differ in the means by which the stereogenic centre was introduced.

Different Strategies for the Chemical Synthesis of Lignans

AbstractFor Abstract see ChemInform Abstract in Full Text.

Alkenyl C—H Insertion of a β‐Disulfone Iodonium Ylide into Flavones.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Direct Methylation and Trifluoroethylation of Imidazole and Pyridine Derivatives.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Alkenyl C–H insertion of a β-disulfone iodonium ylide into flavones

The reaction of phenyliodonium bis(phenylsulfonyl)methylide with flavones affords insertion products into the alkenyl carbon–hydrogen bond of the flavone, presumably by an electrophilic attack of the iodonium ylide on the double bond of the flavone.

Direct methylation and trifluoroethylation of imidazole and pyridine derivatives.

Direct methylation or trifluoroethylation of imidazole and pyridine derivatives using N-methyl bis((perfluoroalkyl)sulfonyl)imides or trifluoroethyl phenyliodonium bis((trifluoromethyl)sulfonyl)imide affords high yields of the corresponding salts. This methodology provides a simple route to a variety of room temperature ionic liquids (RTILs).

Oxidative cyclisation of cis- and trans-2,3-dibenzylbutyrolactones using phenyl iodonium bis(trifluoroacetate) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone

A series of cis- and trans-2,3-dibenzylbutyrolactones have been subjected to oxidative cyclisation using phenyl iodonium bis(trifluoroacetate) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. The products obtained include two novel spirodienones 6 and 11, which rearrange with acid to give the dibenzocyclo-octadienes 7, and 12 and 13, respectively.

Asymmetric syntheses of isostegane derivatives using trivalent iodine reagents

Two asymmetric syntheses of the isostegane derivative (+)-3 are reported, both involving oxidation of a homochira1 2,3-dibenzylbutyrolactone with phenyliodonium bis(trifluoroacetate). Of particular interest is the fact that the oxidative step can be carried out directly on a precursor containing a hemiacetal functional group and leads to the same configuration of the biaryl unit.

Phenylbis(fluorosulfonyl)- and phenylbis(trifluoromethylsulfonyl)-methyliodonium triflates

Phenyliodonium bis(fluorosulfonyl)methylide ( I) and phenyliodonium bis(trifluoromethylsulfonyl)methylide ( II) are converted to triflates of phenylbis(fluorosulfonyl)- ( III) and phenylbis(trifluoromethylsulfonyl)-methyliodonium ( IV), respectively, by the addition of equimolar amounts of trifluoromethanesulfonic acid in CH 2Cl 2. The existence of these triflates has been confirmed by 19F NMR spectroscopy. Reactions between the iodonium salts III and IV and nucleophilic reagents such as thiophenol derivatives, thiocyanates, nitrites and cyanates result in the formation of strong CH acids, i.e. trisubstituted methanes HC(SO 2R) 2Nu, RF, CF 3, formed as tetrabutylammonium salts.

A New and Simple Synthesis of Heterocycle-Fused [c]Thiophenes: Reaction of Heteroaromatic Thioketones with Bis(arylsulfonyl)diazomethanes and Phenyliodonium Bis(phenylsulfonyl)methylide

A new method for the synthesis of heterocycle-fused [c]thiophenes via reaction of aryl heteroaryl thioketones with the carbene precursors, bis(arylsulfonyl)diazomethanes and phenyliodonium bis(phenylsulfonyl)methylide, is described.